1. Field of the Invention
The present invention relates to a process for preparing p-[[p-(phenylazo)phenyl]azo]phenol (C.I. Disperse Yellow 23).
2. Description of the Prior Art
Disperse Yellow 23 has been made historically by diazotizing aminoazobenzene and coupling the resultant diazonium salt into phenol to yield ##STR2## This method requires the making, isolation and handling of aminoazobenzene which has recently been declared to be a dangerous material because of potential carcenogenicity.
Aminoazobenzene has typically been manufactured using somewhat less than one-half mole of benzenediazonium chloride per one-half mole aniline which ensures against the presence of decomposition products of benzenediazonium chloride in the diazotization mixture which could produce unwanted impurities. In production, such impurities are minimized by the above condition, and if formed, are washed out along with excess aniline with water or aqueous hydrochloric acid during isolation of the aminoazobenzene.
It is an object of the present invention, therefore, to provide a process for preparing Disperse Yellow 23 which does not require the prior isolation of aminoazobenzene and which avoids or minimizes the formation of undesired decomposition products of benzenediazonium chloride.